On Tue, Nov 20, 2018 at 11:17:07AM +0100, Christian Ehrhardt wrote:
> There are certain cases e.g. containers where the sysfs path might
> exists, but might fail. Unfortunately the exact restrictions are only
> known to libvirt when trying to write to it so we need to try it.
>
> But in case it fails there is no need to fully abort, in those cases try
> to fall back to the older ioctl interface which can still work.
>
> That makes setting up a bridge in unprivileged LXD containers work.
>
> Fixes: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1802906
>
> Signed-off-by: Christian Ehrhardt <christian.ehrha...@canonical.com>
> ---
> src/util/virnetdevbridge.c | 48 +++++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 22 deletions(-)
>
> diff --git a/src/util/virnetdevbridge.c b/src/util/virnetdevbridge.c
> index 071ebb7b35..cbba3c9652 100644
> --- a/src/util/virnetdevbridge.c
> +++ b/src/util/virnetdevbridge.c
> @@ -113,6 +113,8 @@ static int virNetDevBridgeCmd(const char *brname,
> * or by ioctl on older kernels. Perhaps we could just use
> * ioctl for every kernel, but its not clear what the long
> * term lifespan of the ioctl interface is...
> + * Fall back to ioctl if sysfs interface is not available or
> + * failing (e.g. due to container isolation).
> */
> static int virNetDevBridgeSet(const char *brname,
> const char *paramname, /* sysfs param name */
> @@ -128,29 +130,31 @@ static int virNetDevBridgeSet(const char *brname,
> if (virFileExists(path)) {
> char valuestr[INT_BUFSIZE_BOUND(value)];
> snprintf(valuestr, sizeof(valuestr), "%lu", value);
> - if (virFileWriteStr(path, valuestr, 0) < 0) {
> - virReportSystemError(errno,
> - _("Unable to set bridge %s %s"), brname,
> paramname);
> - return -1;
> - }
> + if (virFileWriteStr(path, valuestr, 0) >= 0)
> + return 0;
> + virReportSystemError(errno,
> + _("Unable to set bridge %s %s via sysfs"),
> + brname, paramname);
The virReportSystemError line should be dropped, since we're not
returning an error - we're moving onto the second code path instead.
> + }
> +
> + unsigned long paramid;
> + if (STREQ(paramname, "stp_state")) {
> + paramid = BRCTL_SET_BRIDGE_STP_STATE;
> + } else if (STREQ(paramname, "forward_delay")) {
> + paramid = BRCTL_SET_BRIDGE_FORWARD_DELAY;
> } else {
> - unsigned long paramid;
> - if (STREQ(paramname, "stp_state")) {
> - paramid = BRCTL_SET_BRIDGE_STP_STATE;
> - } else if (STREQ(paramname, "forward_delay")) {
> - paramid = BRCTL_SET_BRIDGE_FORWARD_DELAY;
> - } else {
> - virReportSystemError(EINVAL,
> - _("Unable to set bridge %s %s"), brname,
> paramname);
> - return -1;
> - }
> - unsigned long args[] = { paramid, value, 0, 0 };
> - ifr->ifr_data = (char*)&args;
> - if (ioctl(fd, SIOCDEVPRIVATE, ifr) < 0) {
> - virReportSystemError(errno,
> - _("Unable to set bridge %s %s"), brname,
> paramname);
> - return -1;
> - }
> + virReportSystemError(EINVAL,
> + _("Unable to set bridge %s %s via ioctl"),
> + brname, paramname);
> + return -1;
> + }
> + unsigned long args[] = { paramid, value, 0, 0 };
> + ifr->ifr_data = (char*)&args;
> + if (ioctl(fd, SIOCDEVPRIVATE, ifr) < 0) {
> + virReportSystemError(errno,
> + _("Failed to set bridge %s %s via ioctl"),
> + brname, paramname);
> + return -1;
> }
>
> return 0;
Regards,
Daniel
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